Such lawn mowers according to the state of the art have been offered on the market repeatedly in the past and have disappeared from the market again after some time. In these lawn mowers, the battery is a built-in part of the lawn mower and is connected permanently to it by way of cables, attachments, covers, etc. The battery weight is thus part of the lawn mower weight. The lawn mower is therefore significantly heavier than standard lawn mowers with single phase electric motor that are powered via a cable from the power mains. The disadvantage of the greater weight is present especially when transporting the lawn mower, e.g. over steps. The battery capacity of the lawn mower is chosen so that at least a specific grass area that is specified by the manufacturer can be mowed with a single discharge of the battery, and is therefore limited. Hereby it is taken into account that the usable capacity of both a lead and a nickel-cadmium battery decreases through use and aging and that mowing conditions themselves differ. According to manufacturers'statements, standard lawn mowers therefore are only capable of mowing approximately 200 m.sup.2 to 300 m.sup.2 areas without recharging, in spite of a heavy lead battery with e.g. 40 ampere hours at 12 volts, or in spite of an expensive nickel-cadmium battery with e.g. 7 ampere hours at 24 volts. In the case of such a lawn mower that was recently introduced on the market, the nickel cadmium battery is supposed to be charged within a short time by a quick-charge device, in order to be able to mow under difficult mowing conditions and to be able to mow larger grass areas. But this means an interruption of the mowing for recharging and requires an expensive quick-charge device.